Man wasn’t designed to sit all day. Our bodies just were not made to do that. Sitting in chairs all day is unnatural. Our ancestors were very physical and in a lot of countries that are not westernized, a physical and more natural 
type of lifestyle still exists. African women are a prime example. They stand erect and have perfect posture moving with the grace and poise of a lion. They are the strongest women in the world.
For those of us who sit in a chair all day long, as typical office jobs require, has us putting our bodies in a position that adds stress to the spine. To avoid developing or compounding back problems, it’s important to have an office chair that’s ergonomic, supports the lower back and promotes good posture.
Things to consider are:
- Seat height. Should be easily adjustable. A pneumatic adjustment lever is the easiest way to do this. A seat height that ranges from about 16 to 21 inches off the floor should work for most people. This allows the user to have his or her feet flat on the floor, with thighs horizontal and arms even with the height of the desk.
- Seat width and depth. The seat should have enough width and depth to support any user comfortably. Usually 17-20 inches wide is the standard. The depth (from front to back of the seat) needs to be enough so that the user can sit with his or her back against the backrest of the ergonomic office chair while leaving approximately 2 to 4 inches between the back of the knees and the seat of the chair. The forward or backward tilt of the seat should be adjustable.
- Lumbar support. Lower back support in an ergonomic chair is very important. The lumbar spine has an inward curve, and sitting for long periods without support for this curve tends to lead to slouching (which flattens the natural curve) and strains the structures in the lower spine. An ergonomic chair should have a lumbar adjustment (both height and depth) so each user can get the proper fit to support the inward curve of the lower back.
- Backrest. The backrest of an ergonomic office chair should be 12 to 19 inches wide. If the backrest is separate from the seat, it should be adjustable in height and angle. It should be able to support the natural curve of the spine, again with special attention paid to proper support of the lumbar region. If the office chair has the seat and backrest together as one piece, the backrest should be adjustable in forward and back angles, with a locking mechanism to secure it from going too far backward once the user has determined the appropriate angle.
- Seat material. The material on the office chair seat and back should have enough padding to be comfortable to sit on for extended periods of time. Having a cloth fabric that breathes is preferable to a harder surface.
There you go. Now armed with a few facts you can go find the right comfort, not just for your butt, but also for your back. Posture and comfort is everything. Remember too that a regular exercise program is key. Exercise does not have to be strenuous and gut wrenching. Simple daily stretches and walking are very helpful to the body that sits all day.
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